1. Field of the Invention
The present invention relates to a wafer transporting apparatus, and, more particularly, to a wafer transporting apparatus for use in an electron beam measuring apparatus, an electron beam lithography apparatus, an electron beam surface observing apparatus or the like used for semiconductor production or inspection and a wafer supporting carrier which is used for such a wafer transporting apparatus.
2. Description of the Related Art
The conventional wafer transporting apparatus may generally be classified into three following types.
In a first type, a wafer is pressed against fixed pins by a movable pin to fix the wafer on a wafer holding carrier device and a contact member for grounding the wafer extends from the wafer surface to break through a resist film, an oxide film or the like on the wafer so that the contact member is electrically connected to the wafer.
In a second type, a wafer is held on a carrier and its outer peripheral portion is gripped by suitable members disposed at a bottom side of the wafer and urged by a spring force, and a needle urged by a flat spring is provided in a pressure plate disposed at the top side of the wafer to be used as a grounding contact for grounding the wafer, as shown in Japanese Utility Model un-examined publications JP-A-62-172149 (U) or JP-A-57-44543 (U).
In a third type, a wafer is held on a carrier by virtue of an electrostatic attracting force based on an electric power supplied even during the transport of the wafer from an atmospheric environment to an X-Y stage which is placed in a vacuum environment and where further processing such as measurement, lithographic processing or inspection of the wafer is conducted.
In the first type of conventional apparatus, it is difficult to maintain the flatness over the surface of the wafer since only the outer peripheral portion of the wafer is fixed. Therefore, there is a problem in that a large dimensional error is locally produced upon measurement or lithographing due to a change of the degree of flatness of the wafer. Also, there is a problem in that the wafer grounding contact member causes the deposition of undesired substances on the wafer surface.
Also in the second type of conventional apparatus, it is difficult to maintain the flatness of the wafer. Like the first type of conventional apparatus, the second type of conventional apparatus has a problem in that a large dimensional error is locally produced upon measurement or lithographing due to a change of the degree of flatness of the wafer.
In the third type of conventional apparatus in which the wafer is fixed by virtue of the electrostatic attracting force, a supply of a DC electric power is required even during the transport of the wafer from the atmospheric environment to the X-Y stage in the vacuum environment. Therefore, it is difficult to simplify a transporting mechanism or a complicated transporting mechanism having parts for insulation and power supply incorporated therein is required.